How do I link certain fields from one issue to another issue?

[Peter Hyde-Smith]

I have premade labels with serial numbers that I put on all of my IT hardware. These obviously do not match up with the normal issue linking key. 

I have created a custom field to enter in these serial numbers.

When I have a helpdesk issue that is associated/caused by a certain piece of hardware, I want to be able to type that serial number in the "link issue" box and connect the Asset Issue and the Trouble Ticket.

I do not want to use a labels custom field.

[Nic Brough -Adaptavist-]

You'll need to write a new field to do this, one that understands the relationship in full.